1. Field of the Invention
This invention relates to a photonic crystal and a method of fabricating the photonic crystal, and more particularly, to a photonic crystal fabricated by an electrophoretic deposition technique, and a method of fabricating the photonic crystal.
2. Description of Related Art
A photonic crystal has a periodic dielectric distribution, and may be in one, two, or three-dimension. Light interference occurs when light passes a periodically arranged structure. A photonic band gap is generated when the constructive interference increases and the destructive interference decreases, and light is thus limited and controlled to have high reflectivity and high dispersion.
In terms of the functionality, one-dimensional, two-dimensional, and three-dimensional photonic crystals have more applications in various field. A one-dimensional photonic crystal may be a film, such as an anti-reflective film and a total reflection film. A two-dimensional photonic crystal may be a waveguide, a beam splitter, or an interferometer. A three-dimensional photonic crystal may comprise a plurality of nano-scaled, densely and periodically arranged particles.
A one-dimensional photonic crystal is fabricated by growing layers of material that have moderate thickness and reflectivity by a technique to form a semiconductor plating film. Development and etching processes are used to fabricate a two-dimensional photonic crystal, that is, periodically arranging a high-k material, or forming an air column (low-k material) on a silicon substrate. As shown in FIG. 1, a photonic crystal fiber 1 comprises an array of air columns 10 that are formed in a semiconductor 11 by the development process. However, the development process is complicated, time-consuming, hight-cost, and low-yield and is hardly used to fabricate a three-dimensional structure. The development process is further limited by an etching aspect ratio in a semiconductor process, the perpendicularity of top and bottom threshold sizes of holes etched, and the length of a photonic crystal. Accordingly, the photonic crystal fiber 1 has a limited application.
A very large-scale integrated-circuit (VLSI) fabrication technology may be used to fabricate a three-dimensional photonic crystal that has a periodically arranged photonic crystal structure. A wafer lithography process or a process that combines optical and chemical mechanical polishing may be also used to fabricate a similar structure. A gravity sedimentation method and a solution evaporation method are two of the most popular crystal fabricating methods in the art to fabricate a three-dimensional structure. However, it takes a long time to prepare a photonic crystal in the gravity sedimentation method, and the solution evaporation method may form a self-assembly layer that has visible wave stripes, and a plating layer thus has no moderate thickness.
Therefore, how to develop a new-generation technique for fabricating a three-dimensional photonic crystal that has any desirable geometric, periodically arranged structure is becoming one of the most urgent issues in the art.